Sherman — whose helmet was off at the time — waved at Williams as the two were separated.

“It’s just a dirty move by Trent Williams, that’s all it was,” Sherman said. “I could understand why he’s frustrated. It’s the end of their season. They played a solid game, but (that was) just a cheap shot.”

Williams said afterward he was out of line.

“Just high emotions, man,” Williams said in comments distributed after the game. “I let them get the best of me. It’s nobody’s fault but mine. I’ve got to calm down a little bit.”

Clemons injured

Seattle defensive end Chris Clemons had to leave the game because of a knee injury he suffered in the second half.

Coach Pete Carroll said the team would need magnetic-resonance imaging (MRI) before determining the severity of the injury, but indicated it is potentially serious.

“We’re concerned about it,” Carroll said.

Clemons led the team with 11.5 sacks during the regular season, his third consecutive season with 10 or more sacks. He is one of only three players in the NFL to have 10 or more sacks in each of the past three seasons.

Rookie Bruce Irvin stepped into Clemons’ role after the injury, but pass pressure remains a concern. Seattle had two sacks in the game, and they have totaled just three sacks over the past 12 quarters.

Beltway rush hour

There was no secret about either team’s intention Sunday.

The Seahawks ran the ball more often than any other team during the regular season, Washington ranked No. 2.

Washington enjoyed the early advantage as rookie Alfred Morris carried on two of the team’s first three plays for a total of 17 yards. That set the tone for a first quarter in which Washington gained 61 yards on the ground during its two touchdown drives.

“At first, we were just out of whack,” said Seattle linebacker K.J. Wright. “We weren’t fitting how we were supposed to be, we weren’t getting off of blocks.”

The Seahawks got that straightened out, though.

Washington ran for just 43 yards over the final three quarters.

“They had a good scheme,” Sherman said. “They knew how to attack us. But once they figured out how to attack us, we just manned up and everybody stood up.”

Notes

• The attendance for the game at FedEx Field was announced at 84,325, the most ever to watch a playoff game at the stadium. “They’re nowhere near as loud as home,” Sherman said, comparing it to Seattle’s CenturyLink Field. “They’ve got more people, but they don’t make enough noise.”

• Seattle held an edge in turnover ratio, forcing two from Washington as safety Earl Thomas intercepted a pass in the first half and defensive tackle Clinton McDonald recovered a fumble. Marshawn Lynch’s third-quarter fumble resulted in Seattle’s only turnover. Under Carroll, the Seahawks are 18-4 when they force more turnovers than they commit. They are 3-14 when they have a negative turnover differential.

• John Moffitt was active for the first time in three weeks, and he saw time at right guard behind starter J.R. Sweezy.